Effect of Methodological Choices on Pavement Life-Cycle Assessment (original) (raw)
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Transportation Research Part D: Transport and Environment, 2014
In order to assess sustainability of products and processes, different methodologies have been developed and used in the last years. In the road pavement construction area, most methodologies used for life cycle assessment (LCA) are essentially focused in the construction phase. The present paper analyses the importance of the use phase of a road in the LCA of different paving alternatives, namely by evaluating energy consumption and gaseous emissions throughout the road pavement's life. Therefore, a new LCA methodology for road pavements was developed, and the results of its application to a case study involving the construction of alternative pavement structures are discussed. The study intends to assess the influence of using more sustainable paving construction alternatives (asphalt recycling vs. conventional asphalt mixtures), and/or different surface course materials (which have a higher influence on the rolling resistance and, therefore, affect the performance during the use phase). The LCA results obtained for this case study showed that the reductions in energy consumption and gaseous emissions obtained during the use phase, for pavement alternatives with a lower rolling resistance surface course, are higher than the total amount of energy consumption and gas emissions produced during construction. It is therefore clear that some improvements in the characteristics of the surface course may have an effect over the road use phase that will rapidly balance the initial costs and gas emissions of those interventions. The LCA results obtained also showed that the sustainability of pavement construction may also be improved using recycled asphalt mixtures.
Life Cycle Environmental Assessment Using Athena Pavement LCA Tool: A Manitoba Case Study
2016
Environmental sustainability is one of the four strategic priorities of the Department of Manitoba Infrastructure. Life Cycle Assessment (LCA) is acknowledged as one of the most comprehensive ways to evaluate the environmental impacts of different strategies associated with a physical feature. The Athena Pavement LCA software for highways is a tool that can be used to assess the environmental impacts of materials production, construction, and maintenance & rehabilitation activities over a given life cycle period. The software is also capable of modeling pavement vehicle interactions (PVI) to assess the environmental impact of traffic use phases of a roadway due to pavement surface roughness and deflection. This paper presents comparisons of the environmental impacts of various alternative strategies for a concrete pavement to demonstrate the opportunity to optimize pavement performance and environmental impacts. The concrete pavement constructed in 2015 on Manitoba Provincial Truck Highway 75 (PTH 75) has been used as a case study. A matrix of alternative concrete mix, pavement design, and maintenance and rehabilitation strategies has been used to compare environmental impacts of those alternative options. The analysis presented is expected to assist Manitoba Infrastructure and other agencies to better understand and weigh the environmental implications of alternative roadway materials, design as well as construction, maintenance and rehabilitation practices and select the best strategy considering pavement performance and preservation of our natural environment.
Comparison of Life-Cycle Assessment Tools for Road Pavement Infrastructure
Transportation Research Record: Journal of the Transportation Research Board
Road pavements have considerable environmental burdens associated with their initial construction, maintenance, and usage, which have led the pavement stakeholder community to join efforts to understand and mitigate these negative effects better. Life-cycle assessment (LCA) is a versatile methodology for quantifying the effect of decisions regarding the selection of resources and processes. However, there is a considerable variety of tools for conducting pavement LCA. This paper provides the pavement stakeholder community with insights into the potential differences in the life-cycle impact assessment results of a pavement by applying American and European LCA tools, namely, PaLATE Version 2.2, the Virginia Tech Transportation Institute–University of California asphalt pavement LCA model, GaBi, DuboCalc, and ECORCE-M, to a Spanish pavement reconstruction project. Construction and maintenance life-cycle stages were considered in the comparison. On the basis of the impact assessment m...
2016
for their spiritual encouragement. I would also like to extend my thanks to Mr. Hans, Concha, and staff CTIS UTEP. I would like to thank my family in India for putting up with an absentee son and brother during this dissertation and for their everlasting support. To my loving, understanding, and supportive wife, Niharika: my deepest gratitude. Your encouragement when the times got rough are much appreciated and duly noted. Finally, to my lovely daughter Aarna, she has been my stress buster and brought joy and life to the home. vi Executive Summary A sustainable pavement can be defined as the one that minimally impacts future economic opportunities, social conditions, human health, and the environment and still fulfills the engineering objectives. Although a pavement as outlined above is not yet entirely feasible, continual effort from every stakeholder with a vision of achieving sustainable development is essential for the future of society. In this study, one such effort was initiated by proposing a framework for selection of pavement design based on sustainable development. The concept of sustainability is widely believed to be founded on three criteria: economic, environmental, and social standards. Since the purpose of pavements it to provide service for many decades, assessing each criterion throughout the life of pavements is required, that is, based on life cycle assessments. Based on the review of information, the most widely used economic evaluation tool for pavements is Life Cycle Cost Analysis (LCCA), which has been proposed by the Federal Highway Administration (FHWA). Practitioners have started using Life Cycle Assessment (LCA) recommended by the International Organization for Standardization (ISO), which has been recently adopted by the FHWA to estimate environmental impacts. Although various tools are Brundtland et al. (1987) Sustainability is not about threat analysis, sustainability is about systems. Specifically, it is about how environmental, economic, and social systems interact to their mutual advantage or disadvantages at various space based scales of operation.
Considering the benefits of asphalt modification using a new technical LCA framework
Asphalt mixtures properties can be enhanced by modifying it with additives. Even though the immediate benefits of using polymers and waxes to modify the binder properties are rather well documented, the effects of such modification over the lifetime of a road are seldom considered. To investigate this, a newly developed open technical life cycle assessment (LCA) framework was used to determine production energy and emission limits for the asphalt additives. The LCA framework is coupled to a calibrated mechanics based computational framework that predicts the in-time pavement performance. Limits for production energy of wax and polymers were determined for the hypothetical case studies to show how LCA tools can assist the additives manufacturers to modify their production procedures and help road authorities in setting 'green' limits to get a real benefit from the additives over the lifetime of a road. From the detailed case-studies, it was concluded that better understanding of materials will lead to enhanced pavement design and could help in the overall reduction of energy usage and emissions.
Selected road condition, vehicle and freight considerations in pavement life cycle assessment
Road condition affects the operations and costs of vehicles using the infrastructure, as well as the rate at which the road deteriorates during use. Therefore, active and timely management of the road condition can be used as a tool to extend the service life of a road. One of the objectives of pavement Life‐Cycle Assessment (LCA) is to evaluate the consequences of changes to a system on the entire life cycle and thus all relevant issues that may affect the operation of the system. It provides a comprehensive approach to evaluating the total environmental burden of a road, examining all the inputs and outputs, including material production, road construction, road use, maintenance and rehabilitation and end‐of life phases for road infrastructure. This paper focuses on issues that are directly affected by the road riding quality, and how this can potentially be utilized in LCA. The paper is mainly based on a pilot study conducted for the California Department of Transportation (Caltr...
A LCCA Methodological Approach for the Feasibility Study of Pavement Types
Life Cycle Cost Analysis (LCCA) has been a significant tool for the study of Economic Analysis and Comparison. In an engineering point of view cost optimization is very important during Planning and Design Phase. Engineering Technology comes up with immense solutions and opportunity to the problems. To find the solution whether economically feasible or not Life Cycle Cost Analysis has been used as a tool in this paper. In this study a segment of road was taken under consideration. The road sections were designed for the expected increment of AADT. A calculation is performed for 20yr analysis period for 1km length of both type of pavements considering all standard maintenance and rehabilitation works. RHD Schedule of Rates (June, 2011) was taken to calculate the expected construction costs and Maintenance and Rehabilitation Costs. Discount Rate of 5% and predicted Monitory Inflation Rate have been considered for 20yr analysis period. Finally the Life Cycle Cost has been calculated and compared for both types of Pavement. A graphical representation of the Life Cycle Costs has been shown. The outcome of the research was as- Flexible Pavements costs 3 times more to Rigid Pavement in 20yr analysis period for 1km length of each type of pavements and after 7 years of lifetime the costing for HMA Pavement exceeds the costing of Rigid Pavement.
Role of Uncertainty Assessment in LCA of Pavements
2016
Life Cycle Assessment (LCA) is a tool to appraise the environmental impact of a pavement during its service life. Typically, the LCA assessor has to make some assumptions and judgments, employ data from different sources, use analytical tools and models, etc., in order to provide information to the transportation officials for decision making. Since assumptions and data from different sources have inherent uncertainty, it is essential to explicitly report the underlying uncertainties and their consequences in LCA outputs. This study recommends an approach for performing uncertainty assessment in pavement LCA. The first step of the recommended approach is to define a clear objective for the need of the assessment. Then establish the scope of assessment such that it is technically feasible and satisfies the assessment objective. Prioritizing the phases in LCA that influence the output and concentrating only on significant phases makes the uncertainty assessment viable. The next step i...
Sustainability
This study used a cradle-to-cradle Life Cycle Assessment (LCA) approach to evaluate the environmental potentials of urban pavements. For this purpose, the urban road network of the City of Münster (Germany) was selected as the case study, and comprehensive data for several phases were collected. The entire road network is composed of flexible pavements designed according to specific traffic loads and consists of main roads (MRs), main access roads (MARs), and residential roads (RSDTs). Asphalt materials, pavement structures, and maintenance strategies are predefined for each type of road and are referred to as “traditional” herein. Some pavement structures have two possible maintenance strategies, denoted by “A” and “B”, with distinguished periods of intervention. To evaluate the impact of using recycled materials, we considered alternative pavement structures composed of asphalt materials containing a greater amount of reclaimed asphalt pavement (RAP). The study was carried out con...
Pavement Materials Evaluation Through a Two-Stage Life Cycle Analysis Approach
A two-stage life cycle analysis approach for alternative screening of structural solutions is introduced in this study and applied to a case study to assess the environmental loadings of different road pavements alternative during construction. It was found that the combined damage caused by Acidification and Eutrophication is the most significant, and the damage to resources caused by fossil fuels followed. The other effects seem not so important within relatively neglectable low scores. In addition, based on the comparison of natural aggregate structure and the blast-furnace slag pavement structure, the latter one is recommended due to less environmental loadings. The results of sensitivity analysis also proved the robustness of the proposed approach. However, a number of assumptions applied in both phases would lead to limitations in applying the approach to other fields, and further studies on uncertainty analysis would be desirable.